Methods and nodes for controlling uplink power in a radio network

ABSTRACT

A method and network node for controlling power of uplink transmissions from a user node when switching between a first operating mode and a second operating mode. The network node signals to the user node a first value of a maximum allowed transmit power to be applied when operating in the first operating mode and a second value of the maximum allowed transmit power to be applied when operating in the second operating mode. The user node then uses a transmit power not exceeding the first value when transmitting radio signals in the first operating mode, and uses a transmit power not exceeding the second value when transmitting radio signals in the second operating mode. The user node itself thereby regulates the transmit power depending on opera mode without requiring further signalling from the network node.

TECHNICAL FIELD

The present disclosure relates generally to a network node, a user nodeand methods therein, for controlling uplink transmission power for theuser node when switching between different operation modes.

BACKGROUND

In traditional radio networks for wireless communication, such as GSMnetworks, a single narrowband frequency carrier is typically used fortransferring data and messages in radio signals between the network anda user node connected to a radio access node of the network, usuallycalled network node or base station, either for transmitting signalsfrom the network node on a downlink connection to the user node or fortransmitting signals from the user node on an uplink connection to thenetwork node. Recently, increasingly advanced user terminals and deviceshave emerged on the market, e.g., smartphones, tablets and wirelesslaptops, which are suitable for services such as internet browsing,streaming of media and any other communication of large amounts of data.The demands for high data throughput has therefore increased. In thisdescription, the term “user node” is used to represent any communicationequipment capable of transmitting radio signals to a radio access nodeof a radio network, such as a base station. The user node in thiscontext could also be referred to as a mobile terminal, mobile station,User Equipment (UE), wireless device, etc., depending on the terminologyused. Further, the term “network node” will be used to represent a nodeof a radio network, that is configured to signal information to a usernode.

To meet the greater demands for data throughput, the possibility ofusing two or more carriers in parallel in a user node has beenintroduced such that the amount of data that can be communicated pertime unit, also referred to as data throughput, is basically multipliedby the number of carriers used. This feature thus introduces multipleparallel carriers transmitted on separate frequencies to or from thesame user node, provided that the user node is capable of usingmulti-carriers. The user node may also employ multiple antennas fortransmitting on multiple carriers. Further, the user node may need toswitch between two different operating modes such as transmitting on asingle carrier or on two or more carriers, basically depending onavailability of radio resources and/or the need for data throughput.

Uplink transmissions from a first user node which occur within a firstsystem band may cause interference to one or more other nodes receivingradio signals within a neighboring second system band since the firstuser node's transmission also causes unwanted emissions outside its ownnominal transmission band, also referred to as “out-of-band” or“spurious” emissions. For example, the first and second system bands maybe used by different network operators having adjacent licensedfrequency bands, or by different cells of a radio network. An examplesituation is illustrated in FIG. 1 where a first network system 1 isconfigured to use a system band for uplink transmissions and a secondnetwork system 2 is configured to use a neighboring system band foreither downlink or uplink transmissions or both.

Even though the uplink band of system 1 and the band used by system 2are separated by a certain guard band in the example shown in thefigure, transmission from the first user node in the uplink band ofsystem 1, denoted “aggressor”, may still cause interference to a secondnode receiving in the neighboring band 104 of system 2, denoted “victimband”. The unwanted emissions on both sides of the nominal uplink band100 are schematically indicated by dotted curves outside the band 100,and a part 102 of the nominal victim band 104 of system 2 coincides withthe emissions from the first user node, thus resulting in interferenceat the second node, particularly if the first and second nodes happen tobe located relatively close to one another.

For example, the victim band 104 may be used for downlink transmissionsand the second node may therefore be a user node. A similar interferencefrom uplink emissions may also occur when the victim band is also usedfor uplink transmissions where the second node is a network node.Another example is when the victim band 104 is used for Time DivisionDuplex, TDD, transmissions alternately switching between downlink anduplink timeslots according to a TDD scheme. Further examples includewhen the victim band 104 is used for other wireless services such aspublic safety, military communication, radar, and so forth.

It is thus a problem that uplink transmissions in a nominal band maycause interference in another adjacent victim band due to unwantedout-of-band emissions that partly coincide with the adjacent victimband. A conventional solution to avoid or at least reduce the aboveinterference is to employ power regulation such that the transmittinguser node is instructed by its serving network node to reduce itstransmission power. This may be implemented by sending or otherwiseproviding a maximum allowed transmit power to the user node, therebyinstruction the user node to use a transmit power not exceeding themaximum allowed transmit power. This maximum allowed transmit power mayalso be preconfigured, e.g., in a standard specification or the like.However, if the user node frequently switches between differentoperating modes, the network node may need to send a new powerregulation order each time the user node has switched its operatingmode.

It is thus another problem that if a user node switches betweendifferent operating modes, the serving network node may need to sendfrequent power regulation orders to the user node which occupy preciousradio resources, and it also takes some time before the user node hasreceived an order and adjusted its transmit power accordingly.Therefore, the user node may still generate the above-described unwantedemissions that may cause interference in an adjacent band, at least fora limited time period before adopting to the power regulation order,each time it has changed its operating mode which may be done repeatedlyand very rapidly, e.g., depending on the current need for datathroughput and available radio resources.

SUMMARY

It is an object of embodiments described herein to address at least someof the problems and issues outlined above. It is possible to achievethis object and others by using a user node, a network node and methodstherein as defined bar the attached independent claims.

According to one aspect, a method is performed by a network node of aradio network, for controlling power of uplink transmissions from a usernode configured to switch between a first operating mode and a secondoperating mode when transmitting radio signals. In this method, thenetwork node signals to the user node a first value of a maximum allowedtransmit power to be applied by the user node when operating in thefirst operating mode and a second value of the maximum allowed transmitpower to be applied by the user node when operating in the secondoperating mode. Thereby, the network node requires the user node to usea transmit power not exceeding the first value when transmitting radiosignals in the first operating mode, and to use a transmit power notexceeding the second transmitting radio signals in the second operatingmode.

According to another aspect, a network node of a radio network isarranged to control power of uplink transmissions from a user nodecapable of transmitting radio signals in a first operating mode and in asecond operating mode. The network node comprises means configured tosignal to the user node a first value of a maximum allowed transmitpower to be applied by the user node when operating in the firstoperating mode and a second value of the maximum allowed transmit powerto be applied by the user node when operating in the second operatingmode. Thereby, the network node is operable to require the user node touse a transmit power not exceeding the first value when transmittingradio signals in the first operating mode, and to use a transmit powernot exceeding the second value when transmitting radio signals in thesecond operating mode.

According to another aspect, a method is performed by a user node forperforming uplink transmissions as controlled by a network node of aradio network, the user node being capable of transmitting radio signalsin a first operating mode and in a second operating mode. In thismethod, the user node receives from the network node a first value of amaximum allowed transmit power to be used when operating in the firstoperating mode and a second value of the maximum allowed transmit powerto be used when operating in the second operating mode. The user nodefurther uses a transmit power not exceeding the first value whentransmitting radio signals in the first operating mode, and also uses atransmit power not exceeding the second value when transmitting radiosignals in the second operating mode.

According to another aspect, a user node is arranged to perform uplinktransmissions as controlled by a network node of a radio network, theuser node being capable of transmitting radio signals in a firstoperating mode and in a second operating mode. The user node comprisesmeans configured to receive from the network node a first value of amaximum allowed transmit power to be used when operating in the firstoperating mode and a second value of the maximum allowed transmit powerto be used when operating in the second operating mode. The user nodealso comprises means configured to use a transmit power not exceedingthe first value when transmitting radio signals in the first operatingmode, and to use a transmit power not exceeding the second value whentransmitting radio signals in the second operating mode.

Advantages that may be achieved when employing any of the above aspectsinclude, without limitation, a reduced risk for interference caused bythe user node when switching between the two operating modes, which willbe explained in more detail below.

The above methods and nodes may be configured and implemented accordingto different optional embodiments to accomplish further features andbenefits, to be described below.

BRIEF DESCRIPTION OF DRAWINGS

The solution will now be described in more detail by means of exemplaryembodiments and with reference to the accompanying drawings, in which:

FIG. 1 is a diagram illustrating how uplink transmissions in one systemband may cause interference in another system band.

FIG. 2a and FIG. 2b are diagrams illustrating how different bandwidthtransmissions generate out-of-band emissions.

FIG. 3 is a flow chart illustrating a procedure that may be performed bya network node, according to some possible embodiments,

FIG. 4 is a diagram illustrating an example of how uplink transmissionsmay be distributed for two carriers.

FIG. 5 is a diagram illustrating another example of how uplinktransmissions may be distributed for two carriers.

FIG. 6 is another flow chart illustrating a procedure that may beperformed by a user node, according to further possible embodiments.

FIG. 7 is another flow chart illustrating a procedure that may beperformed by a network node, according to further possible embodiments.

FIG. 8 is a block diagram illustrating a user node and a network node inmore detail, according to further possible embodiments.

DETAILED DESCRIPTION

Briefly described, a solution is provided which can be used to avoid orat least reduce the risk for interference caused by a user node whenswitching between two operating modes that generate different amounts ofunwanted emissions outside a normal uplink band or frequency range,which emissions may coincide with another band or frequency range thatmay be used by a victim system, or by another communication entity or byanother service, or similar.

Unwanted emissions immediately outside a used nominal band or frequencyrange are typically generated from the modulation process andnon-linearity in the transmitter in the user node, whereas emissionfurther away in frequency, i.e., spurious emissions, are typicallycaused by unwanted transmitter effects such as harmonics emission,parasitic emission, intermodulation products and frequency conversionproducts. These effects are typically reduced when the output power ofthe transmitter is reduced. Moreover, the wider the aggressor channelbandwidth, the wider the unwanted spectral emissions.

The increased demand for mobile services in a radio network hasincreased the need for allocation of additional spectrum for mobileservices. This also means that the frequency separation betweenoperating bands designated for mobile services and bands intended forother services will be reduced such that the risk of harmfulinterference between services increase. Embodiments described in thisdisclosure may be used for reducing such harmful interference caused bythe unwanted emissions outside the nominal band. It should be noted thatthe described embodiments may be useful regardless of whether theunwanted emission is categorized as out-of-band or spurious. Forsimplicity, the term “out-of-band” is used in this description withoutlimitation. The solution may be used e.g., to meet certain spuriousemission requirements being enforced on transmissions in a nominal bandor frequency range, for whatever reason.

It is thus recognized that more or less out-of-band emissions aregenerated depending on the operating mode used, such as single carriertransmission versus multiple carrier transmission, or single antennatransmission versus multiple antenna transmission. In general, multiplecarrier transmission and/or multiple antenna transmission potentiallygenerate more out-of-band emissions than single carrier transmissionand/or single antenna transmission, which will be explained in moredetail below. The used operating ay further involve different featuressuch as different modulation schemes, antenna configurations, uplinkMultiple-Input-Multiple-Output, MIMO, and uplink transmit diversity, tomention a few non-limiting examples which may generate different amountsof out-of-band emissions.

It is further recognized that the range in frequency of such unwantedemission becomes greater when the range of a used nominal bandincreases, which is illustrated in FIGS. 2a and 2b . In FIG. 2a , anominal band of relatively narrow bandwidth “NB” is used by atransmitting user node e.g., when operating in an operating mode where asingle carrier and/or a single antenna is used. The unwanted emission ispartly illustrated on frequencies above the nominal band of NB, by thecurve 200. The unwanted emission in this case exceeds a certain emissionlevel “E” over a certain frequency range denoted “x”. The same appliesfor frequencies below the nominal band of NB, not shown. The emissionlevel E may be deemed critical in the sense that it may potentiallycause interference to another node in an adjacent victim band.

In FIG. 2b , a nominal band of relatively wide bandwidth “WB” is used bythe user node e.g., when operating in another operating mode where amultiple carrier and/or multiple antennas are used. The unwantedemission 202 on frequencies above the nominal band of WB in this caseexceeds the critical emission level E over a frequency range “y” that isconsiderably greater than x in FIG. 2a . The same applies forfrequencies below the nominal band of WB, not shown. It is thusrecognized that the risk for interference in an adjacent victim band isgreater when the user node is operating on the wide bandwidth WB in thesecond operating mode than when operating on the narrow bandwidth NB inthe first operating mode.

Consequently, the user node must be instructed to transmit with lowerpower when operating on WB in the second operating mode, as compared tothe first operating mode, in order to reduce the frequency range y thatexceeds the critical emission level E and thus avoid or at leastalleviate the potential interference the transmission might cause on anadjacent victim band. On the other hand, the user node should bepreferably allowed to transmit with the higher power again whenreturning to operate on NB in the first operating mode, e.g., to achieveadequate reception of the transmitted signals. As mentioned above, somedisadvantages occur when the network node is required to issue a newpower regulation order each time the user node changes its operationmode, which may happen quite frequently, including excessive signalingover the radio interface and the extra time it takes for the user nodeto adopt each new required power level. Embodiments of the solution tobe described below can be used to avoid the need for sending a new powerregulation order each time the user node changes its operation mode, asfollows.

When the user node is expected to or anticipated to switch between thefirst and second operation modes, e.g., at least once, the network nodein this solution signals to the user node two different values of amaximum allowed transmit power to be applied by the user node dependingon which operating mode it operates in. Thereby, the user node is ableto adapt its transmission power level on its own according to thesignaled values when switching between operation modes, withoutrequiring any additional power regulation orders from the network node.An example of how this may be done will now be described with referenceto the flow chart in FIG. 3 which illustrates actions performed by anetwork node which is arranged to control power of uplink transmissionsfrom a user node capable of transmitting radio signals in a firstoperating mode and in a second operating mode.

The network node in this procedure may be implemented in a radio networkcontrolling node such as the well-known Radio Network Controller RNC, orin a base station, depending on how the network is configured, althoughthe solution is not limited to these examples. If the network node isimplemented in an RNC or similar, any signaling and messages therefromare actually transmitted by an associated base station currently servingthe user node which base station also receives any radio signalstransmitted by the user node.

An optional first action 300 illustrates schematically that the networknode may instruct the user node to transmit radio signals, e.g., withdata and/or control signaling, in an uplink band that is adjacent toanother band that may potentially be interfered by the user node'stransmitted radio signals, hence a victim band. In another action 302,the network node signals to the user node a first value of a maximumallowed transmit power to be applied by the user node when operating inthe first operating mode and a second value of the maximum allowedtransmit power to be applied by the user node when operating in thesecond operating mode. Thereby, the user node is effectively required touse a transmit power not exceeding the first value when transmittingradio signals in the first operating mode, and to use a transmit powernot exceeding the second value when transmitting radio signals in thesecond operating mode. This action does not exclude that the networknode may signal more than two values of the maximum allowed transmitpower to the user node, e.g., also a third value and so forth, which areto be applied by the user node when operating in further operating modessuch as a third operating mode and so forth.

A further optional action 304 illustrates that the network node itselfmay actually configure the user node to transmit signals in the firstoperating mode with a power not exceeding the signaled first value, andto transmit signals in the second operating mode with a power notexceeding the signaled second value. This action may alternatively beperformed by the serving base station if the network node is implementedin an RNC or similar. In practice, and depending on the implementation,the above actions 300-304 may be performed by triggering the servingbase station to transmit one or more suitable control messagescontaining at least the first and second values of the maximum allowedtransmit power to the user node. Such control messages may also containan indication of any uplink radio resources allocated to the user nodefor the transmission of radio signals, e.g., with data and/or controlsignaling, according to regular procedures.

The above procedure may be performed in accordance with various possibleoptional embodiments. In some possible embodiments, the network node maybe configured to signal the first and second values by broadcastingsystem information or by sending a dedicated message to the user node.An advantage with using dedicated messages to different user nodes isthat different values of the second value can be sent to different usernodes. This may for example depend on the minimum distance between theuplink carriers used by the user nodes and the frequency range thatneeds to be protected, i.e., the victim band, since the amount ofrequired power reduction may vary between different user nodes, e.g.,depending on if the secondary carrier occupies a frequency range that islower or higher than the primary carrier. It is also possible to updatealready signaled values of the maximum allowed transmit power bysignaling to the user node. For example, it may be desirable to applyand signal one or more new values to the user node if it has moved toanother geographic area and/or cell, if the traffic load has changed, ifthe need to protect the victim band has changed, depending on time ofday or week, and so forth.

In further possible embodiments, the network node may be configured tosignal the first and second values as follows. For example, in UTRA(UMTS Terrestrial Radio Access), it is specified that an uplink powerlimitation denoted “Maximum allowed UL TX power” can be indicated by thenetwork in the broadcasted System Information Block type 3 or in thebroadcasted System Information Block type 4, and in other dedicatedmessages transmitted to the user node. The first value may be signaledas an existing channel information element as defined in the 3GPPdocument TS 25.331 as:

-   -   MaxAllowedUL-TX-Power::=INTEGER (−50..33)        In this case, the second value may be signaled as a new channel        information element which could be further defined in TS 25.331        as:    -   AdditionalMaxAllowedUL-TX-Power::=INTEGER (−50..33)

This new channel information element may be likewise indicated in thebroadcasted System Information Block type 3 or in the broadcasted SystemInformation Block type 4, and in other dedicated messages transmitted tothe user node.

In another possible embodiment, the first operating mode may comprisesingle carrier transmission and the second operating mode may comprisemultiple carrier transmission, which was also mentioned above. Forexample, the above-mentioned “Maximum allowed UL TX power” may applywhen single-carrier transmission is used while the “Additional maximumallowed UL TX power” may apply when dual-carrier transmission is used.In another possible embodiment, when multiple carriers are used in thesecond operating mode, the user node may be required use a totaltransmit power not exceeding the second value for all carriers used inthe second operating mode, to ensure that the total transmission on themultiple carriers limited to avoid or at least reduce any harmfulinterference the transmission might cause on an adjacent victim band.

Different definitions may be employed for when a user node is consideredto operate in a first or a second operating mode, and for when theassociated maximum allowed transmit power should be applied. Again,using single or multiple carrier operation as a non-limiting example, auser node may be considered to operate in a second operating mode assoon as the network has configured the user node to use multiple carrieroperation, which may be done by signaling from an RNC of a UMTS network.In this case, the network signals to the user node what frequency to usefor each secondary carrier and other information necessary tocommunicate with the network on this secondary carrier. Alternatively, auser node may be considered to operate in a second operating de as soonas the network has activated the secondary carrier for the user node,which may be done by signaling from a serving base station. Anotheralternative is that a user node may be considered to operate in a secondoperating mode as soon as the network, e.g., the serving base station,has sent a non-zero scheduling grant for the secondary carrier to theuser node. As yet another alternative, a user node may be considered tooperate in a second operating mode only during time instants when it isactually transmitting signals on both the primary and the secondarycarrier.

It is also possible to restrict the transmission power depending on howmany carriers are used in the second operating mode while the secondvalue should be applied for exactly two carriers. Thus, in anotherpossible embodiment, the network node may be configured to instruct theuser node to reduce the second value by a “carrier-specific offset” foreach additional carrier more than two carriers. For example, it may beappropriate to reduce the second value by a specific carrier-specificoffset CSO, e.g., 1 dB, such that the signaled second value is reducedby (N−2)×CSO when N carriers are used and N>2.

In another possible embodiment, when multiple carriers are used in thesecond operating mode, the single carrier transmission may be applied inthe first operating mode on a primary uplink frequency and the multiplecarrier transmission may be applied in the second operating mode on aprimary uplink frequency and at least one secondary uplink frequency.Some examples of this are illustrated in FIGS. 4 and 5. In FIG. 4, afirst carrier frequency 400 is used as the primary uplink (UL) frequencyand a second carrier frequency 402 is used as the secondary uplinkfrequency such that the first carrier frequency 400 is closest to avictim band. When both carrier frequencies 400 and 402 are used in thesecond operating mode, i.e., two carriers over a relatively wide band,more unwanted out-of-band emissions will be generated as compared towhen only carrier frequency 400 is used in the first operating mode,i.e., a single carrier over a relatively narrow band.

In FIG. 5, on the other hand, a first carrier frequency 500 is used asthe primary uplink frequency and a second carrier frequency 502 is usedas the secondary uplink frequency such that the second carrier frequency502 is closest to a victim band. Similar to FIG. 4, when both carrierfrequencies 500 and 502 are used in the second operating mode, i.e., twocarriers, more unwanted out-of-band emissions will be generated ascompared to when only carrier frequency 500 is used in the firstoperating mode, i.e., a single carrier. In this case however,transmissions only in the first carrier frequency 500 in FIG. 5 willcause less interference in the victim band than the first carrierfrequency 400 in FIG. 4 since carrier frequency 400 is closer to thevictim band than the first carrier frequency 500 in FIG. 5. Therefore,when using only the primary uplink frequency in the first operatingmode, a higher maximum power may potentially be allowed in theconfiguration of FIG. 5 than in the configuration of FIG. 4.

When the secondary uplink frequency is activated, the power limitationindicated in the second value, e.g., the channel information element“Additional maximum allowed UL TX power”, applies to the sum of theoutput power of the primary uplink frequency and the secondary uplinkfrequency. When the secondary uplink frequency is deactivated, the powerlimitation indicated in the first value, e.g., the channel informationelement “Maximum allowed UL TX power”, applies to the output power ofthe primary uplink frequency. Further, in a future release of thestandard, it may be allowed to use more than one secondary uplinkfrequency simultaneously. In one such embodiment, the power limitationindicated in the second value, e.g., the channel information element“Additional maximum allowed UL TX power”, applies to the sum of theoutput power of all currently activated carriers.

It was mentioned above that different features in the user node maygenerate different amounts of out-of-band emissions. In yet anotherpossible embodiment, the network node may, by suitable signaling, beconfigured to instruct the user node to adjust the second value by a“feature-specific offset” when at least one feature is activated in theuser node. The at least one feature may pertain to any of:

-   -   A used modulation scheme, recognizing that different modulation        schemes may generate different amounts of unwanted emissions        outside the nominal band.    -   A used antenna configuration, recognizing that different antenna        figurations may generate different amounts of unwanted emissions        outside the nominal band.    -   Usage of uplink MIMO, recognizing that MIMO may generate a        different amount of unwanted emissions outside the nominal band        as compared to when MIMO is not employed.    -   Usage of uplink transmit diversity, recognizing that uplink        transmit diversity may generate a different amount of unwanted        emissions outside the nominal band as compared to when uplink        transmit diversity is not employed.

The use of a configured output power may thus depend on featuresdescribed by various radio parameters, e.g., as exemplified above. Somenon-limiting examples of this could thus include the use of higher-ordermodulation, e.g., 16 QAM/4 PAM for High Speed Uplink Packet Access,HSUPA, and the use of different antenna configurations and transmissionmodes, e.g., uplink MIMO or uplink transmit diversity. Furthermore, thesecond value, e.g., the channel information element “Additional maximumallowed UL TX power” may be applied depending on different combinationsof one or more different radio parameters, e.g., the use of 16QAM and anactivated secondary uplink frequency. Since this allows for manydifferent combinations, more than one new signaled value may berequired, which can be accomplished in several ways. As non-limitingexamples, some different values of a maximum allowed transmit power tobe applied for different combinations may be defined using new physicalchannel information elements as follows:

-   -   MaxAllowedUL-TX-Power-DualCarrier::=INTEGER (−50..33)    -   MaxAllowedUL-TX-Power-16QAM::=INTEGER (−50..33)    -   MaxAllowedUL-TX-Power-MIMO::=INTEGER (−50..33)    -   MaxAllowedUL-TX-Power-DualCarrier-16QAM::=INTEGER (−50..33)

Further, it is possible to define information elements as the abovesecond value and further values of the maximum allowed transmit powerthat would apply a certain offset or the like related to the first valueof the maximum allowed transmit power e.g., depending on what featuresare active. In yet another possible embodiment, the network node maythus be configured to signal the second value as a modification of thefirst value, e.g., in the form of an offset or the like. Thus, thesecond value may be signaled as a specific reduction of the first value,e.g., 5 dB, implying that the second value equals the first value minus5 dB.

An example of how the user node of the above examples may operate willnow be described with reference to the flow chart in FIG. 6 whichillustrates actions performed by a user node which is arranged toperform uplink transmissions as controlled by a network node of a radionetwork. It is assumed that the user node is capable of transmittingradio signals in a first operating mode and in a second operating mode.The network node in this procedure may be the network node describedabove for FIG. 3. An optional first action 600 illustrates schematicallythat the user node may receive an instruction from the network node totransmit radio signals, e.g., with data and/or control signaling, in anuplink band that is adjacent to another band that may potentially beinterfered by the user node's transmitted radio signals, hence a victimband. This action basically corresponds to action 300 in FIG. 3.

In another action 602, the user node receives from the network node afirst value of a maximum allowed transmit power to be used whenoperating in the first operating mode and a second value of the maximumallowed transmit power to be used when operating in the second operatingmode. This action basically corresponds to action 302 in FIG. 3 wherethe network node signals the first and second values to the user node,either by broadcasting or by sending a dedicated message to the usernode.

If the user node determines in an action 604 to operate in the firstoperating mode, the user node uses a transmit power not exceeding thefirst value when transmitting radio signals in the first operating mode,as shown by an action 606. On the other hand, if the user nodedetermines in action 604 to operate in the second operating mode, theuser node uses a transmit power not exceeding the second value whentransmitting radio signals in the second operating mode, as shown by anaction 608. In either case, the user node may at some point change itsoperating mode in an action 610 such that the procedure returns toaction 604 to determine operating mode and use a transmit poweraccordingly, and so forth. Thereby, the user node only needs to receivethe first and second values of the maximum allowed transmit power once,and no further power regulation orders are needed which thus savesfurther resource consuming and time consuming signaling from the networkto the user node.

The embodiments described above are also applicable in this procedure ofFIG. 6. Thus, the first operating mode may comprise single carriertransmission and the second operating mode may comprise multiple carriertransmission. In that case, the user node may be configured to use atotal transmit power not exceeding the second value for all carriersused in the second operating mode. The user node may further beconfigured to be instructed by the network node to reduce the secondvalue by a carrier-specific offset for each additional carrier more thantwo carriers. The user node may further be configured to apply thesingle carrier transmission in the first operating mode on a primaryuplink frequency and to apply the multiple carrier transmission in thesecond operating mode on a primary uplink frequency and at least onesecondary uplink frequency. The first operating mode may also comprisesingle antenna transmission and the second operating mode may comprisemultiple antenna transmission.

In further embodiments, the user node may be configured to receive thefirst and second values from the network node as broadcasted systeminformation or as a dedicated message to the user node. The user nodemay further be configured to receive the first value as an existingchannel information element (MaxAllowedUL-TX-Power) and to receive thesecond value as a new channel information element(AdditionalMaxAllowedUL-TX-Power)

The user node may further be configured to be instructed by the networknode to adjust the second value by a feature-specific offset when atleast one feature is activated in the user node, the at least onefeature pertaining to any of:

-   -   modulation scheme,    -   antenna configuration,    -   usage of uplink Multiple-Input-Multiple-Output, MIMO, and    -   usage of uplink transmit diversity.        The user node may further be configured to receive the second        value as a modification of the first value.

Another procedure performed by the above network node according to someof the above embodiments will now be described with reference to theflow chart in FIG. 7. An optional first action 700 illustrates that thenetwork node may instruct the user node to transmit radio signals in anuplink hand that is adjacent to a victim band, as in action 300. Anotheraction 702 illustrates that the network node signals to the user nodethe above-described first and second values of a maximum allowedtransmit power, as in action 302. Actions 700 and 702 are thus basicallythe same as actions 300 and 302.

In this example, multiple carriers are used by the user node, the numberof carriers being denoted N. Another action 704 thus illustrates that Ncarriers are activated for the user node. In a further action 706, thenetwork node configures the user node to specifically transmit radiosignals in the second operating mode with a power not exceeding thesecond value adjusted by (N−2)×CSO, where CSO is a predefinedcarrier-specific offset value. Effectively, the user node will adjustthe received second value by one CSO value for each added carrier morethan two. Thereby, the user node is able to change the number ofcarriers used and adjust its maximum power accordingly, withoutrequiring any further signaling from the network node, such that anoptimal maximum allowed transmit power will be applied when using anynumber of carriers.

The block diagram in FIG. 8 illustrates a detailed but non-limitingexample of how a network node 800 and a user node 802, respectively, maybe structured to bring about the above-described solution andembodiments thereof. In this figure, the network node 800 and the usernode 802 may be configured to operate according to any of the examplesand embodiments of employing the solution as described above, whereappropriate, and as follows. Each of the network node 800 and the usernode 802 is shown to comprise a processor “P”, a memory “M” and acommunication module “C” with suitable equipment for transmitting andreceiving signals with information in the manner described herein.

The communication module C in the user node 802 comprises suitable radiocircuitry configured for radio communication with a base station BSserving the user node 802 while the communication module C in thenetwork node 800 of this example is configured for communication withthe base station BS. Alternatively, the network node 800 may beimplemented in the serving base station BS and in that case thecommunication module C in the network node 800 comprises radio circuitryconfigured for radio communication with user nodes such as the user node802.

The network node 800 comprises means configured or arranged to performat least the actions 302-304 of the flow chart in FIG. 3 in the mannerdescribed above. These actions may be performed by means of a module inthe processor P in the network node 800 as follows. The network node 800is arranged to control power of uplink transmissions from the user node802 capable of transmitting radio signals in a first operating mode andin a second operating mode.

The network node 800 comprises a signaling module 800 a which isconfigured to signal to the user node a first value of a maximum allowedtransmit power to be applied by the user node when operating in thefirst operating mode and a second value of the maximum allowed transmitpower to be applied by the user node when operating in the secondoperating mode. Thereby, the user node is required to use a transmitpower not exceeding the first value when transmitting radio signals inthe first operating mode, and to use a transmit power not exceeding thesecond value when transmitting radio signals in the second operatingmode.

The user node 802 comprises means configured or arranged to perform atleast the actions 602-608 of the flow chart in FIG. 6 in the mannerdescribed above. These actions may be performed by means of differentmodules in the processor P in the user node 802 as follows. The usernode 802 is arranged to perform uplink transmissions as cot trolled bythe network node 800, the user node 802 being capable of transmittingradio signals in a first operating mode and in a second operating mode.

The user node 802 comprises a receiving module 802 a which is configuredto receive from the network node 800 a first value of a maximum allowedtransmit power) be used when operating in the first operating mode and asecond value of the maximum allowed transmit power to be used whenoperating in the second operating mode. The user node 802 also comprisesa transmitting module 802 b which is configured to use a transmit powernot exceeding the first value when transmitting radio signals in thefirst operating mode, and to use a transmit power not exceeding thesecond value when transmitting radio signals in the second operatingmode.

It should be noted that FIG. 8 illustrates various functional modules inthe network node 800 and the user node 802, respectively, and theskilled person is able to implement these functional modules in practiceusing suitable software and hardware. Thus, the solution is generallynot limited to the shown structures of the network node 800 and the usernode 802, and the functional modules 800 a and 802 a-b may be configuredto operate according to any of the features described in thisdisclosure, here appropriate.

The functional modules 800 a and 802 a-b described above can beimplemented in the network node 800 and the user node 802, respectively,by means of program modules of a respective computer program comprisingcode means which, when run by the processor P in each node causes thenetwork node 800 and the user node 802 to perform the above-describedactions and procedures. Each processor P may comprise a single CentralProcessing Unit (CPU), or could comprise two or more processing units.For example, each processor P may include a general-purposemicroprocessor, an instruction set processor and/or related chips setsand/or a special purpose microprocessor such as an Application SpecificIntegrated Circuit (AMC). Each processor P may also comprise a storagefor caching purposes.

Each computer program may be carried by a computer program product ineach of the network node 800 and the user node 802 in the form of amemory having a computer readable medium and being connected to theprocessor P. The computer program product or memory M in each of thenetwork node 800 and the user node 802 thus comprises a computerreadable medium on which the computer program is stored e.g., in theform of computer program modules or the like. For example, the memory Min each node may be a flash memory, a Random-Access Memory (RAM), aRead-Only Memory (ROM) or an Electrically Erasable Programmable ROM(EEPROM), and the program modules could in alternative embodiments bedistributed on different computer program products in the form ofmemories within the respective network node 800 and user node 802.

The solution described herein may be implemented by a computer programcomprising instructions which, when executed on at least one processor,cause the at least one processor to carry out the actions according toany of the above embodiments. The solution may also be implemented in acarrier containing the above computer program, wherein the carrier isone of an electronic signal, optical signal, radio signal, or computerreadable storage medium.

Advantages of the above-described solution and its embodiments includereduced signalling, low interference and efficient power regulation, asexplained above. In particular, for uplink single- and multiple-carriertransmission, the possibility to indicate differentiated powerlimitations by the first and second values, respectively, means that theoutput power of the user node can be optimized for each transmissionmode while still avoiding or reducing an unwanted emission level in anadjacent victim band. In prior procedures, both single- andmultiple-carrier transmission are constrained by the same maximumallowed transmit power. If a more stringent limitation is needed formultiple-carrier transmission in order to meet an unwanted emissionlimit in an adjacent victim band, the prior procedures would also impactand reduce the uplink coverage when single-carrier transmission isconfigured which is not the case when using the embodiments describedherein.

While the solution has been described with reference to specificexemplary embodiments, the description is generally only intended toillustrate the inventive concept and should not be taken as limiting thescope of the solution. For example, the terms “radio network”, “usernode”, “network node”, and “operating mode”, have been used throughoutthis description, although any other corresponding entities, functions,and/or parameters could also be used having the features andcharacteristics described here. The solution is defined by the appendedclaims.

What is claimed is:
 1. A method performed by a user node for performinguplink transmissions, the user node being capable of transmitting radiosignals in a first operating mode and in a second operating mode, themethod comprising: using a transmit power not exceeding a first valuefor maximum allowed transmit power when transmitting radio signals inthe first operating mode; and using a transmit power not exceeding asecond value for maximum allowed transmit power when transmitting radiosignals in the second operating mode, wherein the user node transmitswith lower power when operating in the second operating mode as comparedto when operating in the first operating mode.
 2. The method of claim 1,wherein the first operating mode comprises single carrier transmissionand the second operating mode comprises multiple carrier transmission.3. The method of claim 2, wherein the user node uses a total transmitpower not exceeding the second value for all carriers used in the secondoperating mode.
 4. The method of claim 2, wherein the user node isinstructed by the network node to reduce the second value by acarrier-specific offset for each additional carrier more than twocarriers.
 5. The method of claim 1, wherein the single carriertransmission is applied in the first operating mode on a primary uplinkfrequency and the multiple carrier transmission is applied in the secondoperating mode on a primary uplink frequency and at least one secondaryuplink frequency.
 6. The method of claim 1, wherein the first operatingmode comprises single antenna transmission and the second operating modecomprises multiple antenna transmission.
 7. The method of claim 1,wherein the method further comprises first receiving at least one of thefirst and second values via broadcast signaling from a network node. 8.The method of claim 1, wherein the method further comprises firstreceiving at least one of the first and second values via dedicatedsignaling from a network node.
 9. The method of claim 1, wherein themethod further comprises receiving, from a network node, an updatedvalue for each of at least one of the first and second values.
 10. Auser node configured to perform uplink transmissions, the user nodebeing configured to transmit radio signals in a first operating mode andin a second operating mode, the user node comprising: a transmittercircuit; a receiver circuit; a processor operatively coupled to thetransmitter circuit and the receiver circuit; and a memory operativelycoupled to the processor and storing instructions for execution by theprocessor, the instructions being configured so that the processor isconfigured to control the transmitter circuit to: use a transmit powernot exceeding a first value for maximum allowed transmit power whentransmitting radio signals in the first operating mode; and use atransmit power not exceeding a second value for maximum allowed transmitpower when transmitting radio signals in the second operating mode,wherein the user node transmits with lower power when operating in thesecond operating mode as compared to when operating in the firstoperating mode.
 11. The user node of claim 10, wherein the firstoperating mode comprises single carrier transmission and the secondoperating mode comprises multiple carrier transmission.
 12. The usernode of claim 11, wherein the user node uses a total transmit power notexceeding the second value for all carriers used in the second operatingmode.
 13. The user node of claim 11, wherein the instructions areconfigured so that the processor controls the receiver circuit toreceive an indication by the network node to reduce the second value bya carrier-specific offset for each additional carrier more than twocarriers.
 14. The user node of claim 10, wherein the instructions areconfigured so that the processor applies single carrier transmission inthe first operating mode on a primary uplink frequency and appliesmultiple carrier transmission in the second operating mode on a primaryuplink frequency and at least one secondary uplink frequency.
 15. Theuser node of claim 10, wherein the first operating mode comprises singleantenna transmission and the second operating mode comprises multipleantenna transmission.
 16. The user node of claim 10, wherein theinstructions are configured so that the processor controls the receivercircuit to first receive at least one of the first and second values viabroadcast signaling from a network node.
 17. The user node of claim 10,wherein the instructions are configured so that the processor controlsthe receiver circuit to first receive at least one of the first andsecond values via dedicated signaling from a network node.
 18. The usernode of claim 10, wherein the instructions are configured so that theprocessor controls the receiver circuit to receive, from a network node,an updated value for each of at least one of the first and secondvalues.